Exploring visible light enhancement for sensing: an azo-dye decorated gold nanoantenna monitored with a smartphone app

Optical sensors can be used to detect a variety of substances ranging from diagnostics on biological samples to the detection of hazardous substances. This type of sensor can be a valuable alternative to more complex analytical techniques, being fast and requiring little to no sample preparation at the expense of the reusability of the device. Here, we show the construction of a colorimetric nanoantenna sensor using gold nanoparticles (AuNPs) embedded in poly(vinyl alcohol) (PVA) and decorated with the methyl orange (MO) azo dye (AuNP@PVA@MO) that is potentially reusable. As a proof of concept, we apply this sensor to detect H2O2 both visually and using a smartphone-based app for colorimetric measurements. Furthermore, through chemometric modeling of the app data, we can reach a detection limit of 0.0058% (1.70 mmolL(-1)) of H2O2 while being able to visually detect changes on the sensor. Our results reinforce the combination of nanoantenna sensors with chemometric tools as guidelines for sensor design. Finally, this approach can lead to novel sensors allowing for the visual detection of analytes in complex samples and their quantification using colorimetry.

Automated summary

Optical sensors can detect various substances, from biological samples to hazardous substances. In this study, a colorimetric nanoantenna sensor using gold nanoparticles embedded in poly(vinyl alcohol) and decorated with a dye was constructed. The sensor demonstrated potential reusability and was used to visually detect H2O2 with a smartphone-based app. Chemometric modeling of the app data allowed for a detection limit of 0.0058% of H2O2 and visual observation of sensor changes, supporting the combination of nanoantenna sensors with chemometric tools for sensor design. This approach has the potential to enable visual detection and colorimetric quantification of analytes in complex samples.